In blown-film extrusion of LLDPE-rich liner grades, POLYBATCH™ Light Grey 80426U concentrate based in LLDPE is metered at 2.0–4.0 wt% through a gravimetric feeder at the main feed throat, and the first process check is not visual pellet distribution but the pressure trace across a 60/80 mesh screen pack. Because the exact pigment loading and carrier melt index for this grade are not publicly disclosed, the let-down must be adjusted against a supplier CIELAB colour reference measured on the final film thickness rather than on injection-moulded plaques. Processing is carried out on a single-screw extruder with 25:1–30:1 L/D and a barrier screw, with melt temperature held at 190–240 °C, die gap 1.4–2.0 mm, blow-up ratio 2.2:1–3.0:1, and frost line height set at 5–8 die diameters to prevent web instability and optical mottle. The target gauge for industrial liners is 50–80 µm; tensile properties are tested under ASTM D882, tear resistance under ASTM D1922, and dart impact under ASTM D1709 when the film is used for load-bearing construction covers. Compliance for non-food industrial film is established under REACH Regulation (EC) No 1907/2006 Article 33 SVHC communication and Annex XVII restrictions, together with RoHS Directive 2011/65/EU Annex II restricted substance limits; if the liner is intended for indirect food contact, the final film must demonstrate compliance with Commission Regulation (EU) No 10/2011 Annex I and FDA 21 CFR 177.1520, but the concentrate alone does not provide a food-contact certificate. Terminal products include industrial can liners, renovation dust containment sheeting, temporary construction covers, and transport wrapping. Operational boundary: above 6.0 wt%, die lip plate-out risk increases in long runs; if the base resin is HDPE rather than LLDPE, the carrier resin mismatch should be checked by capillary rheometry under ISO 11443 because LLDPE-rich domains can reduce strain hardening during bubble expansion at high draw ratios.

What changes when an LLDPE-carrier light grey concentrate is let down in HDPE extrusion blow moulding?

At addition levels above 3.0 wt% in HDPE extrusion blow moulding, the LLDPE carrier in POLYBATCH™ Light Grey 80426U introduces a lower-viscosity domain that alters parison weight distribution, pinch-off weld thickness, and drop impact after low-temperature conditioning. The recommended validation window is 1.5–3.0 wt%; at 2.0 wt% addition to a base HDPE with ISO 1133-1 MFR of 0.3–0.7 g/10 min at 190 °C/2.16 kg, production-scale blow moulding typically shows no detectable shift in ESCR when measured according to ASTM D1693, but published data for this specific concentrate configuration is limited and first-article approval must compare bottle drop impact after 48 h storage at −20 °C. Extrusion is conducted on a continuous shuttle or accumulator-head machine with melt temperature 180–220 °C, die tooling sized for 55–65 % parison swell, mould temperature 15–40 °C, and blow air pressure 0.6–1.0 MPa. The concentrate is dry-blended at the hopper; pre-drying is not normally required unless condensation from cold storage is visible, in which case dry-air purge at 60 °C is applied before feeding. Regulatory documentation for industrial non-food containers cites REACH Regulation (EC) No 1907/2006 Article 33 and RoHS Directive 2011/65/EU Annex II; if containers are used for regulated dangerous goods, the final wall thickness, top load, and closure performance must satisfy the UN Model Regulations independent of the masterbatch. Terminal products include light grey jerrycans for light-sensitive liquids, automotive washer fluid reservoirs, and rigid intermediate bulk container components. Operational boundary: the LLDPE carrier is not a compatibiliser for polypropylene; above 2.0 wt% in PP-based blow moulding, immiscible domains can reduce Charpy notched impact under ISO 179-1, and the melt may exhibit surface roughness at the parison vent.

Extrusion coating and lamination of woven polyolefin fabrics with a light grey LLDPE concentrate

Extrusion coating lines place the highest shear demand on the melt curtain, and the grey pigment package in POLYBATCH™ Light Grey 80426U must not disturb the air-gap oxidation kinetics that control adhesion to woven polypropylene or paper substrates. Let-down is adjusted to 4.0–8.0 wt% for coating weights between 15 g/m² and 40 g/m²; the higher end is reserved for specified opacity or light-blocking layers, while the lower end is used for thin flexible lamination where melt-curtain stability governs. Processing uses a single-screw extruder with 28:1–32:1 L/D, a coat-hanger die with 0.6–1.0 mm die gap, melt temperature at the die exit of 260–300 °C, air gap 150–250 mm, and line speed 100–300 m/min. The substrate is corona-treated to 40–48 mN/m immediately before the nip; because the LLDPE carrier lowers melt strength slightly relative to an LDPE control, the die-to-nip distance must be trimmed to keep edge neck-in below 30 mm per side. Food-contact laminated packaging requires the final structure to comply with Commission Regulation (EU) No 10/2011 Annex I and FDA 21 CFR 177.1520; the masterbatch supplier’s supporting documentation must identify the pigment additives and processing aids. Non-food industrial packaging falls under REACH Regulation (EC) No 1907/2006 and RoHS Directive 2011/65/EU Annex II. Terminal product types include laminated woven sacks for mineral and resin packaging, industrial wrap, paper-poly packaging, and barrier pouch exteriors. Process boundary: at addition above 8.0 wt%, the melt curtain can show vertical streaks caused by pigment agglomerates; a 50/80 mesh screen pack and static mixer are mandatory, and the line should be stopped if melt pressure upstream of the screen pack rises by more than 10 % over the clean-screen baseline.

When the grey concentrate is buried in a three-layer blown film core

If co-extruded film uses POLYBATCH™ Light Grey 80426U only in the core layer, the let-down must be calculated on total film weight rather than core weight to avoid over-concentration in the thin skin layers and to prevent interlayer viscosity mismatch. A typical three-layer agricultural or construction film with a 20/60/20 layer ratio and total gauge 120 µm can run a core-layer let-down of 3.0–6.0 wt%, equivalent to 1.8–3.6 wt% of total film. The core extruder is set at 200–230 °C with a die gap of 1.8–2.0 mm and blow-up ratio of 2.0:1–2.5:1. Placing the grey pigment in the core reduces die lip plate-out on the outer skin and improves optical uniformity, but tensile and tear properties must be measured under ISO 527-3 and ASTM D1922 because pigment particles act as stress concentrators at high draw ratios. Compliance for this segment references REACH Regulation (EC) No 1907/2006, RoHS Directive 2011/65/EU Annex II, and EN 13207 if the film is sold in the EU as agricultural silage cover or in an agricultural application. Terminal product types include silage clamp covers, temporary storage covers, light-diffusing agricultural films, and construction enclosure sheets. Process boundary: the grade does not provide UV stabilization unless separately stated in the supplier datasheet; outdoor films require a separate UV masterbatch. Rheology must be verified by capillary rheometry under ISO 11443 at 100 s⁻¹ and 1000 s⁻¹; if the core compound MFR is more than 0.5 g/10 min higher than the skin MFR, die port flow instability may occur. Published data for this specific concentrate in three-layer co-extrusion is limited, so pilot-run bubble stability should be checked before production scale.

Injection moulding of returnable PE handling crates and pallets makes weld-line visibility in multi-gate tools the first indicator of incorrect let-down, and the LLDPE carrier in POLYBATCH™ Light Grey 80426U changes solidification kinetics less than a PP-carrier masterbatch would. The process validation window is 1.5–2.5 wt%; at 2.0 wt% addition to a high-density PE base with ISO 1133-1 MFR of 8–20 g/10 min, the compound is processed on a reciprocating screw with L/D 20:1–25:1, melt temperature 200–250 °C, mould temperature 20–50 °C, injection speed 50–120 mm/s, and holding pressure set at 40–70 % of peak injection pressure. Back pressure is maintained at 0.5–1.5 MPa to disperse the pigment; higher back pressure increases melt residence time and can produce grey-streak defects in thick sections. Compliance for reusable industrial containers cites REACH Regulation (EC) No 1907/2006 Article 33 and RoHS Directive 2011/65/EU Annex II; for food-contact crates, Commission Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520 must be demonstrated on the final article under worst-case reuse conditions. Mechanical evaluation follows ISO 527-2 tensile, ISO 178 flexural, and ISO 179-1 impact; the grey pigment package may reduce notched impact relative to natural material in some systems, so first-article approval must compare against a natural control. Terminal products include collapsible totes, structural foam pallets, agricultural crates, and waste bins. Operational boundary: avoid hot-runner drops with long residence time above 240 °C because the LLDPE carrier can degrade into gel-like surface defects; intermittent lines should be purged after every 4 h of standby.

Surface protection film lines reject optical mottle before the melt curtain reaches the chill roll

Cast film lines demand lower melt temperatures and faster draw than blown film, so the grey pigment dispersion in POLYBATCH™ Light Grey 80426U is evaluated by optical density and gel count rather than by MFR alone. Let-down is set at 3.0–5.0 wt% for film thicknesses of 20–50 µm; below 2.0 wt%, the grey shade may shift visibly when the base resin lot changes, and above 5.0 wt%, chill-roll contact defects can appear as microvoids in machine direction. Processing uses a single-screw extruder with L/D 30:1–35:1, die gap 0.5–0.8 mm, melt temperature 220–270 °C, air knife pressure 0.3–0.6 MPa, and chill roll temperature 20–40 °C. The film is tested under ISO 527-3 tensile, ASTM D882, ASTM D1003 haze, and ISO 8295 coefficient of friction; surface protection applications require 180° peel adhesion to stainless steel to be checked because the pigment package can slightly alter the coefficient of friction at the peel interface. Compliance for industrial non-food cast film follows REACH Regulation (EC) No 1907/2006 Article 33 and RoHS Directive 2011/65/EU Annex II; food-contact wrap would require Commission Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520 compliance for the final film. Terminal products include industrial stretch hoods, surface protection films for sheet metal and appliances, garment bags, and furniture transit wrap. Process boundary: the LLDPE carrier is rheologically compatible with LLDPE-LDPE base-resin blends but not with high-melt-strength PP; addition to PP cast film above 3.0 wt% can generate die-lip crystallization and visible surface haze due to immiscible phases.